Most of the jujube varieties I’ve grown so far are pretty straight up sweet without any tartness to go along with the sweetness. Honey Jar is probably the only variety I’ve tasted that I’d call sweet-tart. (My rootstocks make fruit that are very small, have pleasant tartness, but very little sweetness to go along with it.) I’ve read that Chico is another sweet-tart variety. What other varieties are more the sweet-tart type?
Dr. Yao’s NMSU website (NMSU: Jujubes | Multipurpose) describes two cultivars besides Chico that have a sweet-tart flavor - Chaoyang and Zhongning. I’ve not seen either available for purchase yet.